Hera, who was Zeus's wife, discovered that Leto was pregnant and became very angry. She banned Leto from giving birth on any mainland or island known.

Leto found the island of Delos, which floated and so was not an island nor mainland,and gave birth there. Leto gave birth to Artemis without any problem. However she was in labour with Apollo for nine days and nine nights. Artemis helped Leto to give birth to Apollo.